This invention relates generally to microelectronic photosensitive devices which may be used to convert incident radiation into an electric signal representative of the intensity of that radiation. Such devices may be used to form the imaging array of digital imaging devices such as a digital camera, and other devices.
Photosensitive devices may be formed using integrated circuit technology to create an array of photosensitive detectors. This array produces signals representative of the incident radiation. These signals may be digitized to form a digital representation of the target image. By using microelectronic technology to form an array of sensors, a detecting array of relatively small size may be created. Each of the detectors use relatively little power and may be relatively sensitive to incident radiation.
In some embodiments complementary metal oxide semiconductor (CMOS) technology may be used to form imaging arrays. These arrays may be formed of active pixel sensors (APS) or passive pixel sensors (PPS). In addition charge coupled device (CCD) technology may be used to form imaging arrays.
As the photosensitive devices become smaller in size, the fill factor of these devices, which is the amount of light which they collect, correspondingly decreases absent other corrective measures. Thus, in some embodiments, microlenses may be used to collect light from an area larger than the particular photodetector and focus that incident light on the detector. Generally, the microlens diffracts the incoming light and therefore may adversely affect the light which impacts the photosensitive device.
Therefore, there is a continuing need for improved ways to collect incident light and to focus the greatest possible amount of that light on the photodetectors which form an imaging array.